1. Field of the Invention
The present invention relates to a data processing device and, more particularly, to a data processing device in an audio recording and playback apparatus with an imaging function.
2. Related Art Statement
As is generally known, portable audio recording and playback apparatuses (hereinbelow, referred to as IC recorders) have been put into practical use. This kind of IC recorder converts an audio signal into digital data, stores the digital data in a flash memory serving as a rewritable storage medium, converts the audio data stored in the flash memory into an analog audio signal, and then plays back the analog audio signal.
As the characteristics of the above IC recorder, various operation modes such as recording, playback, fast-forward, and fast-rewind can be selectively operated by operating predetermined switches. For example, when the recording mode is selected, audio data converted as a digital signal is stored in an audio data area and index information (the address of this audio data, recording date and time, and the like) related to the audio data is stored in an index information area, these areas being previously formed in the flash memory.
On the other hand, electronic still cameras which can record not only images but also sounds have been put into practical use. In this kind of electronic still camera, however, the most part of the limited storage capacity thereof has to be used for image recording. Therefore, audio recording time per image is fairly short, for example, tens of seconds.
Japanese Unexamined Patent Application Publication No. 6-22258 discloses an electronic still camera which includes an audio recording medium, separated from an image recording medium, thus realizing a long audio recording time. In this camera, a sound is instantaneously outputted upon image playback, thus relating audio recording to the absolute time of a recording start time of each image.
Further, in the electronic still camera, a release time lag has to be minimized as much as possible in terms of the fundamental performance of the camera. Accordingly, a power switch is disposed separately from the release switch. Simultaneously with turn-on of the power switch, power is applied to the whole of a system including imaging devices such as a CCD and a CMOS sensor. Thus, the system is set in a standby mode so that picture taking can be immediately performed whenever the release switch is pressed.
Under energized conditions, battery power is heavily consumed. Japanese Unexamined Patent Application Publication No. 2001-320626 discloses an electronic still camera in which a power saving mode is set in order to realize lower power consumption while the minimum function of the electronic still camera is being used any time.